A Firefox profile stores all of your important data, such as your bookmarks, history, cookies, and passwords. This article explains how to copy the files to a new profile, lists important files in the profile and describes what information is stored in these files.

If you are having a problem with Firefox then sometimes, rather than trying to find and fix the exact cause of the problem, it is easier just to make a new Firefox profile and copy your most important data over to it. Making a new Firefox profile and then copying over certain files gives you a fresh start while retaining your important personal data.

If you are having a problem with Firefox then sometimes, rather than trying to find and fix the exact cause of the problem, it is easier just to make a new Firefox profile and copy your most important data over to it. The Reset Firefox feature will do this for you automatically.The Refresh Firefox feature will do this for you automatically.

Note: Because your preferences and extensions are often the causes of problems, this article does not explain how to copy these between profiles. Therefore, if you follow the steps in this article, you will have to reinstall your extensions and reconfigure your Firefox preferences afterward.

Copying files between profile folders

Note: Firefox must be closed down while copying files between profile folders.

Open your profile folder:

At the top of the Firefox window, click on the Firefox button, go over to the Help menuOn the menu bar, click on the Help menuAt the top of the Firefox window, click on the Help menu and select Troubleshooting Information. The Troubleshooting Information tab will open.Click the menu button
, click help
and select Troubleshooting Information. The Troubleshooting Information tab will open.

Under the Application Basics section, click on Show FolderShow in FinderOpen Directory. A window with your profile filesfolder will open.

At the top of the Firefox window, click on the Firefox button and then select ExitAt the top of the Firefox window, click on the File menu and then select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit

Click the menu button
and then click ExitQuit

Right-clickHold down the Ctrl key while you click
on a file you want to copy and choose Copy.

Open the new Firefox profile folder.

Right-clickHold down the Ctrl key while you click
inside the profile folder and choose Paste Item.

Repeat steps 2-5 for each file you wish to transfer over to your new profile folder.

While copying your personal data from an old Firefox profile to a new Firefox profile, it is possible that you could copy over the file that is causing the problem you are trying to get rid of! The more files you copy over, the greater the chance of this happening. It is therefore recommended that:

You copy over only the minimal amount of files that contain your most important data that you simply can't live without.

You copy over a few files at a time, and then check that the problem you are trying to get rid of hasn't returned.

Site-specific preferences

permissions.sqlite

This file stores many of your Firefox permissions that are decided on a per-site basis. For example, it stores which sites are allowed to, or blocked from setting cookies, installing extensions, showing images, displaying popups, etc.

Personal dictionary

persdict.dat

This file stores any custom words you have added to Firefox's dictionary. If you have never added a custom word to the Firefox dictionary, then you will not have this file. For more information see How do I use the Firefox spell checker?.

Cookies

cookies.sqlite

Cookies are used by websites for a variety of reasons, some of which include keeping you logged in to a website you have previously logged in to, remembering any preferences a website has allowed you to set, authenticating you as a person who has visited a specific website before, etc.

Security certificate settings

cert8.db

This file stores all your security certificate settings and any SSL certificates you have imported into Firefox.